Ring spinning machines and their operation are well known. Basically, such machines are equipped with a plurality of driven spindles, each of which coaxially supports and drives rotation of a yarn spinning tube, and a ring rail defining a coaxial ring about each spindle with a yarn carrying traveler supported on each ring for delivering yarn to the associated spinning tube. As the spindles are driven to rotate their spinning tubes, the ring rail is reciprocated upwardly and downwardly along the spindles and spinning tubes to apply the yarn carried by each ring traveler to the associated spinning tube to be wound thereabout. To produce a cop-type winding of yarn on the spinning tubes, the ring rail is reciprocated a distance less than the length of the spinning tubes, the extent of the reciprocating motion of the ring rail being incrementally shifted along the spinning tube over the course of the winding operation to wind the yarn about the full length of the spinning tube.
As will be understood, it is desirable in normal practice to operate such a ring spinning machine at as high an operational speed as possible within practical limits, generally determined by the frequency at which yarn breakages occur. Typically, yarn breakages are more frequent during the initial stage of a spinning operation wherein the yarn is being applied in the area of the lower end of the spinning tubes, so that the driven speed of the machine spindles generally must be lower within this initial stage of operation in order to maintain the occurrence of yarn breakages within acceptable limits. Likewise, yarn breakages occur more frequently during the final stages of the winding operation, so that spindle speeds must generally be lowered during this stage of operation as well. During the intervening stage of the spinning operation, however, the spinning machine is normally operated at relatively higher spindle speeds to take advantage of the less frequent occurrence of yarn breakages. In this manner, the ring spinning machine may be operated with the highest overall production speed and greatest practical efficiency while keeping the incidence of yarn breakages within acceptable limits.
It has been recognized that, because of the greater spindle speeds utilized during the intermediate stage of the winding operation performed by a ring spinning machine as abovedescribed, the tension in the yarn being wound correspondingly increases, producing a constriction of the yarn wound along the intermediate portion of each spinning tube. As a result, the yarn occupies a lesser volume on the spinning tubes than the same length of yarn would occupy on a corresponding spinning tube without the tension-related constriction of the yarn and, in turn, the full yarn capacity of the spinning tubes is not realized since additional windings of yarn could be placed in the space left unoccupied by the constricted windings of yarn.